Intramolecular phenylborane complexes with monobasic bidentate Schiff bases

APPLIED ORGANOMETALLIC CHEMISTRYAppl. Organometal. Chem. 2007; 21: 89–97Published online in Wiley InterScience(www.interscience.wiley.com) DOI:10.1002/aoc.1180 Materials, Nanoscience and Catalysis

Intramolecular phenylborane complexes withmonobasic bidentate Schiff basesShweta Gaur1, Nighat Fahmi1, Meera Agarwal2 and R. V. Singh1*

1Department of Chemistry, University of Rajasthan, Jaipur-302 004, India2Department of Zoology, University of Rajasthan, Jaipur-302 004, India

A series of intramolecular complexes with Schiff base ligands having N∩S and N∩O donor systemswere synthesized in an open vessel under microwave irradiation (MWI) using a domestic microwaveoven. The reaction time has been brought down from hours to seconds with improved yield ascompared with the conventional heating. The complexes have been characterized on the basisof elemental analysis, conductance measurements and spectroscopic analysis. Based on the IR,1H NMR, 11B NMR and 13C NMR spectroscopic studies, a tetrahedral geometry has been proposedfor the resulting complexes. The compounds have been screened in vitro against bacteria and fungito test their antimicrobial property and in vivo in male albino rats to test their antifertility property.The testicular sperm density, motility and density of cauda epididymal spermatozoa along withbiochemical parameters of reproductive organs have been examined and discussed. Copyright 2007John Wiley & Sons, Ltd.

KEYWORDS: phenylborane complexes; Schiff base; spectroscopic techniques; antimicrobial and antifertility test

INTRODUCTION

Conventional synthesis suffers from many disadvantages andputs at risk both human health and environment. Greenchemistry as applied to chemical processes is environmen-tally benign (in terms of energy use, auxiliaries, waste, etc.)and always leads to simplification of processes in terms ofchemicals used and steps involved. Recently, the accelera-tion of a wide range of chemical reactions using microwavedielectric heating has been reported.1 This in situ mode ofenergy conversion has many attractions to the chemist,because its efficiency depends on the properties of themolecules.2 Studies of new types of chemotherapeuticallyimportant Schiff bases and metal coordinated drugs arenow attracting much attention.3 Schiff base metal chelatesare important in biological processes, pre-concentration ofmetal ions and catalysis.4 After suitable structural modifica-tions, the derivatives of Schiff bases and metal coordinated

*Correspondence to: R. V. Singh, Department of Chemistry, Univer-sity of Rajasthan, Jaipur-302 004, India.E-mail: [email protected]/grant sponsor: CSIR, New Delhi.Contract/grant sponsor: University Grants Commission, New Delhi,India.

drugs may be used as bioactive materials for medicinesas well as in industry.5,6 The reason for application offluoro-organometallic compounds in the pharmaceutical fieldis their microbial activity.7 Thiosemicarbazones8 are biologi-cally active pharmacophores, besides having good complex-ing ability, and their activity enhances on complexation withmetal ions.9,10 The biological properties of semicarbazonesand thiosemicarbazones are often related to the metal ioncoordination. Borane complexes of Schiff base ligands areknown to function as antimicrobial and antifertility agents.11

There is an immense scope for undertaking systematic stud-ies including the biochemical applications12 of the boranecomplexes with a variety of azomethines. Organoboron com-pounds are attracting attention currently because of theirimportance as synthetic intermediates.13,14 Organoboron com-pounds are used as a source of radicals.15 Boron may playan active role in human brain function16 there is additionalevidence that boron is an essential nutrient for humans.The present situation prompted us to prepare complexesof monobasic bidentate Schiff base ligands. Antifungal andantibacterial activities of these boron complexes have beencarried out to study the role of boron in tetrahedral sur-roundings. The focus of our present communication is the

Copyright 2007 John Wiley & Sons, Ltd.

90 S. Gaur et al. Materials, Nanoscience and Catalysis

exploration of the studies on synthetic, structural and biolog-ical aspects of boron complexes.

EXPERIMENTAL

All the chemicals were dried and purified before use and thepurity was checked by thin layer chromatography (TLC).

Preparation of the ligandsLigands 1,3-dihydro-3-[2-(4-fluorophenyl)-2-oxo-ethylidene]-2H-indol-2-one hydrazine carbothioamide and 1,3-dihydro-3-[2-(4-fluoro-3-methyl-phenyl)-2-oxo-ethylidene]-2H-indol-2-one hydrazine carbothioamide as well as 1,3-dihydro-3-[2-(4-fluorophenyl)-2-oxo-ethylidene]-2H-indol-2-one hydrazinecarboxamide and 1,3-dihydro-3-[2-(4-fluoro-3-methyl-phenyl)-2-oxo-ethylidene]-2H-indol-2-one hydrazine carbox-amide were prepared by reaction of hydrazine carboth-ioamide and hydrazine carboxamide with the respectiveketones in ethanolic medium. The reaction mixture wasrefluxed for 1 h. On cooling, the products were recrystallizedfrom the ethanol and dried in vacuo. Their physical propertiesand analytical data are given in Table 1. The parent ligandsexist in tautomeric forms.

Preparation of the complexesTraditional methodA calculated amount of the ligand dissolved in dry toluenewas added to the dihydroxyphenylborane in unimolar andbimolar ratios. The reaction mixture was refluxed for 10–12 hon a fractionating column and the progress of the reaction wasmonitored by the liberation of azeotrope water–toluene. Afterthe completion of the reaction, excess solvent was distilledoff and products were dried. The resulting products werewashed with dry cyclohexane and then finally dried in vacuofor 3–4 h.

Ecofriendly methodA mixture of dihydroxyphenylborane (11.91–17.11 g) and theligand (6.88–9.13 g) dissolved in dry toluene was taken in anopen borosil beaker and irradiated inside a microwave ovenfor 4–8 min. A drastic reduction in reaction time was thusobserved due to the rapid heating capability of microwaves.The completion of the reaction was examined by TLC (eachafter 1 min). Finally the product was worked up as describedin method A and found to be pure by TLC.

Analytical methods and physical measurementsNitrogen and sulfur17 were estimated by Kjeldahl’s andMessenger’s methods, respectively. Boron was estimatedvolumetrically as boric acid. The UV spectra were recordedon an Hitachi-U-2000 spectrophotometer. The IR spectrawith KBr optics were obtained using the Perkin–Elmer 577grating spectrophotometer. The 1H and 13C NMR spectrawere recorded in DMSO-d6 using TMS as the standard on aJeol AL 300 FT NMR. 11B NMR spectra were scanned using

BFž3 Et2O as an external standard. The molecular weights of

the compounds were determined ebullioscopically.

RESULTS AND DISCUSSION

Reactions of phenylboronic acid with monobasic bidentateligands were carried out in dry toluene and under microwaveirradiation. These reactions may be represented as follows:

PhB(OH)2 + N∩XH −−−→ PhB(OH)(N∩X) + H2O

PhB(OH)2 + 2N∩XH −−−→ PhB(N∩X)2 + 2 H2O

where N∩X is the donor system of the reacting ligand moietyand X = S or O.

The resulting colored solids are soluble in DMF andDMSO. The UV, IR and NMR spectra support theproposed structures. Their low molar conductivity values(10–15 ohm−1 cm2 mol−1) show that they are non-electrolytesin nature.

SPECTROSCOPIC STUDIES

UV spectraThe UV spectra of the ligands and their complexes showbands at ca.275 and 300 nm assignable to π –π∗ transitions.These remain almost unchanged in the complexes. Anotherband due to >C N is observed at 370 nm in the spectra of theligands, which shifts to the higher wavelength (380–385 nm)for organoboron derivatives due to donation of the lone pairof electrons by the nitrogen of the ligand to central boronatom, indicating the delocalization of the electronic chargewithin the chelate ring and thus the stabilizing of the resultingcomplexes.

IR spectraThe band due to ν(C N)18 at 1590–1620 cm−1 registers asubstantial change (20–30 cm−1) in the boron complexes as aresult of increase in bond order showing coordination of theazomethine nitrogen to the boron atom. In 1 : 2 complexes aband due to uncoordinated (C N) appears at ∼1595 cm−1.The bands due to ν(C O) and ν(C S) groups in the spectra ofthe ligands were observed at 1680–1690 and 1020–1050 cm−1,respectively. These bands disappeared in the spectra of thecomplexes, suggesting thereby enolization of the ligands andtheir chelation through amido oxygen and thiolic sulfur.19

In the solid-state IR spectra of the ligands, bands observedin the region 3250–3100 cm−1 are due to ν NH,19 whichdo not appear in the spectra of the complexes showing thedeprotonation of this group. However, in the solution spectraof the ligands an additional band due to ν (SH)/(OH) alsoappears and thus shows tautomerization (Scheme 1). The ν

(OH) band in the case of 1 : 1 boron complexes appears atca. 3450 cm−1. Two sharp bands around 3360 and 3420 cm−1

Copyright 2007 John Wiley & Sons, Ltd. Appl. Organometal. Chem. 2007; 21: 89–97DOI: 10.1002/aoc

Materials, Nanoscience and Catalysis Intramolecular phenylborane complexes 91

Tab

le1.

Syn

thet

ican

dan

alyt

ical

data

ofth

elig

ands

and

thei

rbor

onco

mpl

exes

Rea

ctan

ts,g

(mm

ol)

Tim

e/yi

eld

(h)/

(%)

Tim

e/yi

eld

(min

)/(%

)E

lem

enta

lana

lysi

s(%

)a

Mol

arM

.P.

Tra

dit

iona

lE

cofr

iend

lyM

ol.

SML

igan

dra

tio

Com

poun

dC

olou

r(◦ C

)m

etho

dm

etho

dN

SB

wta

——

—L

1 H(C

17H

13N

4OSF

)O

rang

e18

5—

—16

.15

(16.

48)

9.13

(9.4

3)—

335

(340

)Ph

B(O

H) 2

L1 H

1:1

C23

H18

N4O

2SFB

Ora

nge

red

203

8/56

4/83

12.5

9(1

2.62

)7.

15(7

.22)

2.38

(2.4

3)44

0(4

43)

0.24

(1.9

7)0.

64(1

.97)

PhB

(OH

) 2L

1 H1

:2C

40H

29N

8O2S

2F2B

Bro

wn

295

11/

546/

8914

.52

(14.

61)

8.24

(8.3

6)1.

39(1

.41)

762

(766

)0.

24(1

.97)

1.28

(3.9

5)—

——

L2 H

(C18

H15

N4O

SF)

Ora

nge

165

——

15.7

2(1

5.83

)9.

01(9

.06)

—35

0(3

54)

PhB

(OH

) 2L

2 H1

:1C

24H

20N

4O2S

FBR

edbr

own

205

12/

625/

7811

.91

(12.

23)

6.88

(7.0

0)2.

29(2

.36)

456

(457

)0.

38(3

.12)

1.05

(3.1

1)Ph

B(O

H) 2

L2 H

1:2

C42

H33

N8O

2S2F

2BO

rang

e22

510

/64

8/75

13.9

5(1

4.10

)7.

85(8

.07)

1.32

(1.3

6)78

9(7

94)

0.38

(3.1

2)2.

10(6

.21)

——

—L

3 H(C

17H

13N

4O2F

)O

rang

e15

3—

—17

.11

(17.

29)

——

322

(324

)Ph

B(O

H) 2

L3 H

1:1

C23

H18

N4O

3FB

Ora

nge

195

10/

657/

7612

.98

(13.

09)

—2.

49(2

.52)

425

(427

)0.

26(2

.13)

0.72

(2.1

2)Ph

B(O

H) 2

0.26

(2.1

3)L

3 H1.

44(4

.23)

1:2

C40

H29

N8O

4F2B

Red

222

12/

528/

6814

.42

(14.

83)

—1.

43(1

.47)

730

(734

)—

——

L4 H

(C18

H15

N4O

2F)

Ora

nge

160

——

16.4

8(1

6.58

)—

—33

6(3

38)

PhB

(OH

) 2L

4 H1

:1C

24H

20N

4O3F

BO

rang

ere

d19

810

/55

6/75

12.4

2(1

2.67

)—

2.39

(2.4

4)43

8(4

41)

0.21

(1.7

2)0.

61(1

.72)

PhB

(OH

) 2L

4 H1

:2C

42H

33N

8O4F

2BB

rick

red

210

10/

588/

7514

.53

(14.

69)

—1.

39(1

.41)

760

(762

)0.

21(1

.72)

1.22

(3.4

5)

aC

alcu

late

dva

lues

are

give

nin

pare

nthe

ses.



LnH = L1H, L2H, L3H and L4Hwhere n = 1, 2, 3, 4

X = S, L1H, L2HX = O, L3H, L4H

Scheme 1.

due to the NH2 group remain unaltered in the spectra of thecomplexes. A strong band observed in the spectra of the boroncomplexes in the region 1280–1245 cm−1 can reasonably beassigned to Ph-B grouping. The appearance of ν (B ← N),ν (B–S) and ν (B–O) bands at 1535, 870 and 1024 cm−1,respectively, indicate that the azomethine nitrogen, thiolosulfur and enol oxygen are in coordinative interaction at theboron centre.20

1H NMR spectraThe 1H NMR spectra of the free ligands19 and the complexeswere recorded in DMSO-d6. The spectra of the ligands exhibitsignals due to the –NH of the isatin ring and the –NH of thethiosemicarbazone and semicarbazone. The disappearance ofthe –NH signal of the thiosemicarbazone and semicarbazonein the complexes indicates coordination of the azomethinenitrogen as well as covalent bond formation between boronand sulfur/oxygen. Further, in the spectra of the complexes,a slight downfield shift in the position of aromatic protonsalso indicates the coordination of the azomethine nitrogen tothe boron atom. The appearance of a signal due to NH2 groupat about same position in the ligand and the boron complexesshows the non-involvement of this group in coordination.Data are given in Table 2.

13C NMR spectraThe chemical shift values of the carbon atom attached tothe azomethine nitrogen, thiolic sulfur or amido oxygen

Table 2. 1H NMR spectroscopic data (δ, ppm) of the ligandsand their boron complexes

Compound–NH(ring)

–NH(free) NH2 >C N

Aromatic/Ph–Ba

L1H (C17H13N4OSF) 11.08 10.04 3.16 8.08 7.94–7.54C23H18N4O2SFB 11.22 — 3.56 8.22 8.32–7.96C40H29N8O2S2F2B 11.36 — 3.66 8.34 8.28–7.89

L2H (C18H15N4OSF) 11.12 10.24 2.64 8.12 7.72–6.34C24H20N4O2SFB 11.32 — 2.72 8.26 7.84–6.46C42H33N8O2S2F2B 11.38 — 2.76 8.42 8.04–6.89

L3H (C17H13N4O2F) 10.04 9.72 3.04 7.16 6.95–6.16C23H18N4O3FB 10.36 — 3.26 7.54 7.14–6.64C40H29N8O4F2B 10.28 — 3.34 7.82 7.24–6.78

L4H (C18H15N4O2F) 10.12 10.08 2.98 8.08 7.68–6.65C24H20N4O3FB 10.64 — 3.08 8.26 7.50–6.16C42H33N8O4F2B 10.69 — 3.04 8.34 7.20–6.36

a Merged with aromatic protons.

lends further support to the proposed coordination in thesecomplexes. The heterocylic moiety carbon signals, especiallythose of the carbon atoms directly bonded to the heteroatom,undergo slight upfield shifts relative to the other carbonatoms which remain almost undisturbed. The upfield shift ofthe thiolo carbon and azomethine carbon in the complexesindicate participation of these groups in coordination to the



Table 3. 13C NMR spectroscopic data (δ, ppm) of the ligands and their boron complexes

Compound Amido/thiolo Azomethine carbon Aromatic carbons

L1H (C17H13N4OSF) 178.62 157.66 148.08, 144.05, 136.25, 137.71, 133.22, 132.13C23H18N4O2SFB 165.48 154.63 148.40, 144.51, 136.76, 137.22, 133.05, 132.30.C40H29N8O2S2F2B 166.49 156.72 147.20, 144.10, 136.90, 137.52, 132.64, 132.99L2H (C18H15N4OSF) 172.52 155.12 147.24, 144.28, 136.92, 135.72,130.22, 129.71C24H20N4O2SFB 165.47 148.35 146.58, 144.12, 136.52, 135.40, 130.05, 128.62C42H33N8O2S2F2B 165.86 149.72 146.34, 143.35, 136.09, 135.18, 129.62, 128.62L3H (C17H13N4O2F) 167.65 158.25 148.80, 146.51, 132.40, 130.10, 129.70, 121.80C23H18N4O3FB 161.58 151.38 148.45, 144.87, 132.14, 129.89, 129.56, 121.45C40H29N8O4F2B 162.05 153.10 148.67, 144.62, 132.33, 130.05, 129.47, 121.28C24H20N4O3FB 160.45 155.38 143.49, 127.56, 126.08, 123.14, 121.34, 120.07L4H (C18H15N4O2F) 170.20 160.24 143.66, 127.85, 126.54, 123.32, 122.36, 120.66C42H33N8O4F2B 162.32 154.12 143.35, 127.38, 125.67, 123.04, 121.23, 120.05

boron atom (Table 3).

11B NMR spectra21

The signals in the 11B NMR spectra of the complexeswere observed in the range δ2.1–6.4 ppm, which suggesta tetracoordinated environment around the boron atom andformation of a coordinate bond.

On the basis of the results discussed so far, including ana-lytical and spectroscopic data, a tetracoordinated geometry issuggested for the boron complexes (Scheme 2).

MICROBIAL ASSAY

Fungicidal and bactericidal activities of the ligands and theircorresponding boron complexes against different fungi andbacteria have been recorded in Tables 4 and 5 by the methods

Scheme 2.

reported earlier.22 On the basis of these studies, it may beconcluded that fungitoxicity and bacteriostatic properties ofa compound may be slightly enhanced on chelation with theboron ion.

The free ligands (L1H, L2H, L3H and L4H) and theircomplexes were tested against fungi and bacteria to seetheir growth inhibitory potential towards the test organisms.The antifungal activity was tested against Fusarium oxysporumand Aspergillus niger, and the bacteria used were Escherichiacoli and Staphylococcus aureus. Proper temperature (25–30 ◦C),necessary nutrients and growth media free from other microorganisms were employed for the preparation of culturemedia of fungi and bacteria using aseptic techniques.

In vitro study: fungicidal screening (poisonedfood technique)Potato dextrose agar medium was prepared in flask andsterilized. Accurate amounts of all the compounds wereadded after being dissolved in methanol so as to obtain certainfinal concentrations of 50,100 and 200 ppm. Aliquots of 15 mlmedium were poured in sterilized petriplates. A culture of testfungus was grown on PDA for certain days at the optimumtemperature for growth. A small disc of the fungus culturewas cut with a sterile cork borer and transferred asepticallyinto the centre of petridisc containing the medium with acertain amount of fungi and incubated for 4 days at 25 ± 2 ◦C.The colony diameter was measured after the incubationperiod of growth. The percentage inhibition of growth wascalculated by (C − T)C−1 × 100, where C = growth in control,T = growth in treatment.

Bactericidal screening (inhibition zonetechnique)Flat-bottomed petridisc were used and nearly 15 ml of thebeef extract medium (peptone 5 g, beef extract 5 g, NaCl 5 g,agar–agar 20 g and distilled water 1000ml) were pipetted outinto the petridisc. Then bacterial suspension was added andafter some time bacterial growth was seen in the medium. The



Table 4. Antifungal screening data of the ligands and their corresponding complexes. Average inhibition (%) after 96 h (concentration25, 50 and 100 ppm)

Fusarium oxysporum Aspergillus niger

Compound 50 ppm 100 ppm 200 ppm 50 ppm 100 ppm 200 ppm

L1H (C17H13N4OSF) 34 46 53 54 62 68C23H18N4O2SFB 38 52 60 58 64 69C40H29N8O2S2F2B 39 54 62 58 66 72L2H (C18H15N4OSF) 48 57 60 55 66 70C24H20N4O2SFB 50 58 67 56 61 68C42H33N8O2S2F2B 56 64 70 59 66 69L3H (C17H13N4O2F) 23 34 45 54 60 65C23H18N4O3FB 34 39 50 56 63 67C40H29N8O4F2B 40 48 54 62 68 74L4H (C18H15N4O2F) 28 38 55 53 62 66C24H20N4O3FB 38 44 57 54 67 71C42H33N8O4F2B 48 64 70 62 68 72Standard (Bavistin) 91 100 100 86 98 100

test compounds were dissolved in methanol to give 500 and1000 ppm final concentrations. Paper discs of Whatman no. 1filter paper of 5 mm diameter were soaked in these solutionsof varied concentrations. The discs were dried and placed onthe medium with organism in Petri disc at suitable distances.These Petri discs were incubated for 24 h at 25 ± 2 ◦C andzone of inhibition was measured in mm.

Results of antimicrobial studiesFungicidal and bactericidal screening data show that underidentical experimental conditions the compounds possessantimicrobial properties. However, a few compounds possessgood activity against microorganisms. It is also noteworthythat the complexes are more active than their parent ligandsagainst the same microorganism. This increase in biocidalactivity of the complexes can be explained by the chelationtheory.23 The chelation reduces the polarity of the centralion because of partial sharing of its positive charge with thedonor groups and possible π electron delocalization over thewhole chelate ring. Such chelation increases the lipophiliccharacter of the central atom in complex. The increase inthe lipophilic nature results in an increase in permeabilityof the complex through the lipid layer of the cell membraneof microbes. It is seen that concentration plays an importantrole in inhibiting the growth of microorganisms. At lowerconcentration, inhibition is less severe. Owing to this fact theactivities of the organisms will be slowed down, while athigher concentrations, more enzymes will become inhibited,leading to a quicker death of the organisms.

Biological aspectsExperimental designThe healthy male albino rats were used for the present study.The animals were given commercial pelleted feed and tapwater ad libitum. The temperature of their houses was kept at

24 ± 3 ◦C. No rat mortality occurred during the study period.The rats were weighed weekly and changes recorded. Themating exposure test was done on day 55th of the experiment.The rats were sacrificed 24 h after the last dose (61st day) toperform various tests. The weighed rats were divided intothree groups and each group comprised six rats.

Group I was selected as control and treated with olive oil,0.5 ml/day, which was the vehicle chosen to administer thesynthesized compounds. Group II was treated with L1H5 mg in 0.5 ml/day olive oil and Group III was treatedwith C23H18N4O2SFB 5 mg in 0.5 ml/day olive oil. All thecompounds were given regularly for 60 days.

Table 5. Antibacterial screening data of the ligands and theircorresponding complexes. Diameter of Inhibition zone (mm)after 24 h (concentration 500 and 1000 ppm)

Staphylococcusaureus

Escherichiacoli

Compound 500 1000 500 1000

L1H (C17H13N4OSF) 7 9 6 7C23H18N4O2SFB 8 11 7 10C40H29N8O2S2F2B 10 14 9 11L2H (C18H15N4OSF) 8 10 5 6C24H20N4O2SFB 10 14 9 13C42H33N8O2S2F2B 11 13 9 14L3H (C17H13N4O2F) 3 5 5 6C23H18N4O3FB 7 9 7 9C40H29N8O4F2B 10 12 10 14L4H (C18H15N4O2F) 4 7 4 6C24H20N4O3FB 7 10 6 13C42H33N8O4F2B 9 14 7 14Standard (Streptomycin) 15 17 17 18



Fertility testThe experimental rats were cohabited with normal adultproestrous females in the ratio of 1 : 4. Successful matingwas confirmed by the presence of sperm in vaginal smears.Females were separated and resultant pregnancies werenoted, when dams gave birth. The number and size of littersdelivered were recorded. Fertility was calculated in controlas well as in treated animals.

Body and organ weight measurementsThe animals were sacrificed under light ether anaesthesia. Thereproductive and accessory sex organs (testes, epididymis,seminal vesicle, ventral prostate and vas deferens) werecarefully dissected out and freed from adherent tissues. Theliver was also dissected and separated. The weight of eachorgan was measured with an electronic weighing machine,with a sensitivity of 0.01 g.

Sperm motility and sperm densityThe epididymis exposed by a scrotal incision. A cut was madeat the distal end of the cauda epididymis and spermatozoawere expressed by gentle pressure into a fixed amountof physiological saline to make a sperm suspension. Thesperm suspension was then placed on a glass slide andobserved for forward motility. At least 100 spermatozoa perrat were observed under a microscope using a pre-calibratedmicrometer.

The sperm suspension was placed on a Neubauers chamberof haemocytometer and allowed to settle for 1 h. The numbersof spermatozoa in appropriate squares were counted underlight microscope at 100× magnification. Then with the helpof standard formulae, counts per millilitre were calculated.

HaematologyBlood collected in preheparinized tubes by cardiac punc-ture. Total red blood corpuscles, haematocrit, percentagehaemoglobin, MCV, MCH and MCHC were calculated usingthe standard methods.

RESULTS

Body and organ weightNo significant change in the body weight was observedthroughout the experimental duration in all these groups.On the contrary weight of testes, epididymis, seminal vesicle,ventral prostate and vas deferens was significantly (p < 0.001)reduced in groups II and III compared with the control group(Table 6).

Sperm motility and sperm density24

There was 43.15 and 41.73% reduction in the sperm motilityof the groups II and III, respectively, as compared with thecontrol group. Sperm density in cauda epididymis was foundto be only 8.99 and 6.11% of that in control groups II and III, T

able

6.E

ffect

ofva

rious

com

poun

dson

body

and

orga

nw

eigh

tsof

mal

era

ts

Bod

yw

eigh

t(g)

Tis

sue

wei

ght(

mg/

100

gbo

dy

wei

ght)

Tre

atm

ent

Init

ial

Fina

lT

este

sE

pid

idym

isSe

min

alve

sicl

eV

entr

alpr

osta

teV

asd

efer

ens

Con

trol

(veh

icle

trea

ted

)18

9.00

±07

.24

193.

00±

05.2

412

75.0

0±

39.2

840

6±

07.8

056

3.75

±08

.63

263.

20±

26.6

215

7.66

±12

.63

0.5

mlo

live

oil/

kg.b

ody

wt/

day

for

60d

ays

C17

H13

N4O

SF18

5.00

ns±

06.6

519

2.00

ns±

05.6

479

5.63

ns±

41.6

538

7.45

ns±

06.1

952

8.10

ns±

09.6

915

9.62

ns±

17.6

512

1.01

ns±

12.0

25

mg

in0.

5m

loliv

eoi

l/kg

bod

yw

t/d

ayfo

r60

day

sC

23H

18N

4O2S

FB18

6.00

ns±

07.0

119

1.00

ns±

05.0

472

9.71

ns±

47.7

933

6.33

ns±

06.9

951

9.04

ns±

08.3

213

2.23

ns±

21.6

311

8.24

ns±

11.6

55

mg

in0.

5m

loliv

eoi

l/kg

bod

yw

t/d

ayfo

r60

day

s

Mea

n±

SEM

ofsi

xan

imal

s.ns

=N

on-s

igni

fican

t.∗ p

≤0.

01=

sign

ifica

nt.

∗∗p

≤0.

001

=hi

ghly

sign

ifica

nt.

All

grou

psco

mpa

red

wit

hco

ntro

l.



Table 7. Effects of various compounds on sperm dynamics and fertility of male rats

CompoundSperm motility

(Cauda epididymis) (%)Sperm density (Cauda epididymis)

(million/cm3)Fertilitytest (%)

Control (vehicle treated) 68.65 ± 02.20 35.70 ± 02.90 98 (+ve)0.5 ml olive oil/kg body wt/day for 60 daysC17H13N4OSF 29.62∗∗ ± 03.05 03.21∗∗ ± 00.06 43 (−)5 mg in 0.5 ml olive oil/kg body wt/day for 60 daysC23H18N4O2SFB 28.65∗∗ ± 05.20 2.18∗∗ ± 00.30 68 (−)5 mg in 0.5 ml olive oil/kg body wt/day for 60 days

Mean ± SEM of six animals.ns = Non-significant.∗ p ≤ 0.01 = significant.∗∗ p ≤ 0.001 = highly significant.All groups compared with control.

Table 8. Effect of various compounds on biochemical parameters of male rats

Cholesterol (mg/g) Glycogen (mg/g)

Treatment Testes Liver Testes Liver

Control (vehicle treated) 8.05 ± 00.06 14.05 ± 00.18 03.84 ± 00.10 06.85 ± 00.390.5 ml olive oil/kg body wt/day for 60 daysC17H13N4OSF 09.36∗∗ ± 00.02 14.62ns ± 00.15 01.18∗∗ ± 00.12 05.92ns ± 01.305 mg in 0.5 ml olive oil/kg body wt/day for 60 daysC23H18N4O2SFB 09.85∗∗ ± 00.02 14.91∗∗ ± 00.44 01.11∗∗ ± 00.08 05.10ns ± 02.205 mg in 0.5 ml olive oil/kg body wt/day for 60 days

Mean ± SEM of six animals.ns = non-significant.∗ p ≤ 0.01 = Significant∗∗ p ≤ 0.001 = Highly significantAll groups compared with control

respectively. The motility of sperm in groups II and III wasfound to be sluggish without forward progression comparedwith the controls. The results are summarized in Table 7.

Biochemical parameters25

Highly significant (p < 0.001) increase in the testicularcholesterol levels was observed in groups II and III withrespect to the control. On the other hand, the level ofcholesterol in hepatic tissue did not show significant change.A highly significant decrease (p < 0.001) was observed in theglycogen level of the testes in groups II and III with respectto the control. A non-significant change in the liver glycogenwas observed in all groups (Table 8).

HaematologyThe change in haematological parameters26 was found to beinsignificant in all the groups (Table 9).

DISCUSSION

The weight of testes largely depends on the mass ofspermatogenic cells. The reduction in weight may be the

result of the decreased number of germ cells and elongatedspermatids27 caused by the ligand and its boron complex.The decrease in weight of accessory sex organs may be dueto reduced oestrogenic and/or antiandrogenic28 activities ofthe compounds. The negative fertility test may be attributedto the lack of forward progression and the reduction in thedensity of spermatozoa.29 Changes in testicular biochemicalparameters occurred on treatment with the ligand and itscomplex. Cholesterol is the precursor for the synthesisof testosterone hormones. Any inhibition of androgensynthesis30 will lead to an increase in the cholesterol dueto its less local utilization. This is reflected in our studyas groups II and III had significant increases in testicularcholesterol. An increase in testicular glycogen of treatedanimals may be due to poor utilization of glycogen forenergy due to decrease in phosphorylase activity. Thesefindings match the fact that total weight is decreaseddue to the loss of active cells in testes. No changes inhepatic cholesterol and hepatic glycogen indicate that thesecompounds are not hepatotoxic in the given dosages. It maybe of value that these are also not showing haematologicaltoxicity.



Tab

le9.

Effe

ctof

vario

usco

mpo

unds

onha

emat

olog

yof

mal

era

ts

Com

poun

dR

BC

coun

ts(m

illio

n/m

m3 )

WB

Cco

unts

(mill

ion/

mm

3 )H

aem

atoc

rit

(%)

Hem

oglo

bin

(gm

%)

MC

V(%

)M

CH

(%)

MC

HC

(%)

Con

trol

(veh

icle

trea

ted

)05

.06

±00

.39

8817

.77

±18

9.53

41.0

0±

00.6

513

.96

±00

.62

81.0

2±

00.6

227

.58

±00

.68

34.0

4±

00.9

50.

5m

loliv

eoi

l/kg

.bod

yw

t/d

ayfo

r60

day

sC

17H

13N

4OSF

04.6

5ns±

00.2

788

02.6

5ns±

190.

0039

.48ns

±00

.98

14.5

0ns±

01.2

884

.90ns

±00

.51

31.1

8ns±

00.7

636

.72ns

±00

.91

5m

gin

0.5

mlo

live

oil/

kgbo

dy

wt/

day

for

60d

ays

C23

H18

N4O

2SFB

04.8

9ns±

00.2

888

13.0

1ns±

201.

1341

.38ns

±00

.38

14.6

3ns±

02.0

084

.62ns

±00

.61

29.9

1ns±

00.7

335

.35ns

±00

.52

5m

gin

0.5

mlo

live

oil/

kgbo

dy

wt/

day

for

60d

ays

Mea

n±

SEM

ofsi

xan

imal

s.ns

=no

n-si

gnifi

cant

.∗ p

≤0.

01=

sign

ifica

nt∗∗

p≤

0.00

1=

high

lysi

gnifi

cant

.A

llgr

oups

com

pare

dw

ith

cont

rol.

All the above results indicate the effects of organoboron (III)complexes on the male reproductive system of rats and otherphysiological parameters. Furthermore, the current studystrongly demonstrates that the boron complex is a moreeffective antimicrobial and antifertility agent than the parentligand.

AcknowledgementsThe authors thank CSIR, New Delhi and University GrantsCommission, New Delhi, India for financial support.

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Intramolecular phenylborane complexes with monobasic bidentate Schiff bases

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